This application addresses broad challenge area (15) Translational Science and specific Challenge Topic, 15-AI-106: translational research focused on high priority pathogens and basic research focused on resistance mechanisms. The research described herein can be initiated immediately and completed within two years. The work proposed will maintain or create three full time positions and will require the purchase of products and services from the biotech industry. In the longer term, the outcome of the proposed research may stimulate the economy by greatly reducing employee absenteeism due to influenza illness and eliciting the investment of vaccine companies in the optimization and manufacture of universal influenza vaccines. Specifically, we propose the development of novel influenza vaccine constructs which have the potential to protect against a wide range of antigenically-drifted variant viruses and against multiple subtypes influenza A viruses. The design of these constructs is based on our and others'recent observations that monoclonal antibodies which bind to the conserved stalk region of the influenza A virus hemagglutinin (HA) molecule are both broadly cross-reactive and neutralizing. The identified epitope is highly conformational, comprising portions of both the HA1 and HA2 subunits, and is located in the membrane proximal region of the HA protein. During natural infection or vaccination with conventional influenza vaccines, this region of the HA molecule is thought to be masked by the membrane distal portion of HA, a bulky and highly immunogenic globular head domain. Indeed, the immune response to vaccines currently in use is predominantly targeted against the globular head of HA;since this domain is very poorly conserved, current vaccines protect only against relatively small clusters of closely related strains. We have identified a way of expressing a modified HA molecule which lacks the globular head domain and maintains the structural integrity of the stalk region. This molecule forms the basis for a new generation of influenza vaccines which will induce broadly cross- neutralizing antibodies against the conserved stalk region. Such vaccines have the potential to provide protection against epidemic strains arising over several decades, obviating the need for annual influenza vaccination. In addition, vaccines based on the conserved HA stalk domain are predicted to be effective against influenza viruses of most (perhaps all) of the 16 HA subtypes and therefore to provide protection in the event of an influenza pandemic. PUBLIC HEALTH RELEVANCE: The research we propose is aimed at developing a new influenza virus vaccine which has the potential to protect against many distinct types of influenza virus. If successful, this vaccine could protect recipients against influenza for decades, rather than for just one or two years as the current vaccines do. In addition, since it would work against a broad range of influenza viruses, it would provide protection in the event of an influenza pandemic.